Various forms of timber were creatively integrated to achieve a sustainable, architectural build with a modern industrial theme during the construction of a beach house in Sydney, New South Wales.
From the 90-year-old bridge beam forming the backbone of the house through to the use of cross laminated timber (CLT) and recycled timber, this home represents the future of construction in Australia. CLT proved to be the optimum solution to address the complex site conditions for constructing the beach house on a tight budget. This is also the first CLT house in Australia.
The steep and narrow site with proximate adjacent houses had restricted access, necessitating a quick build with minimal disturbance to neighbours. The lightweight, dual span and cantilever characteristics of CLT allowed elevated construction with reduced foundations, hence minimising excavation and site and flora disturbance.
Prefabrication of the CLT structure allowed rapid construction with reduced traffic, waste, noise and dust pollution. Raw cypress pine cladding minimised exterior maintenance in the marine environment. The solid timber structure and cladding reduced the carbon footprint and improved the thermal performance of the house. Mechanical fixings, physical termite barriers and avoidance of glues and coatings minimised VOC emissions and pesticides.
With the exception of the foundations, the entire structure of the house is built using CLT and Glulam. All suspended floors are CLT, and so are all external and internal walls except for a small portion of the concrete block foundation wall and some internal timber frame walls housing services. The entire roof structure is CLT supported with Glulam beams. Glulam posts and beams were employed to distribute the structural loads over clear spans and support the cantilevers.
A large curved composite Glulam and ply beam support the curved CLT roof edge along the length of the building. Non-visible quality finish was specified for the CLT due to budget constraints and possible site and water damage during container stuffing, shipping and transportation from Austria to the site in Sydney. Nevertheless, exposed CLT was used for the feature walls in the living room, master bedroom and outdoor room to great visual effect.
All Glulam posts and beams were lined on the inside and clad on the outside. The solid CLT structure and timber cladding contributed significantly to the sustainability of the beach house. CLT and Glulam construction reduced the carbon footprint of the timber house. The CLT construction was also cheaper than an equivalent concrete and masonry structure.
The solid timber used in the house works as a carbon sink. CLT is produced in an energy-efficient way with reduced fossil fuel input. The timber was sourced from KLH Austria using spruce with European PEFC certification as renewable resource. Solid cypress pine timber cladding allows further carbon sequestration and is sustainably sourced from Forests NSW to AS4708. The mechanically fixed CLT/Glulam structure and timber cladding can be de-constructed and reused. The relatively lightweight solid timber structure allows large spans and cantilevers suitable for elevated construction on the sloping site. Minimal pier foundations are required, reducing site excavation and disturbance.
The prefabrication of the CLT and Glulam structure not only speeds up construction but also minimises construction waste while improving occupational health and safety on site. The installation of CLT causes minimal pollution with little dust and reduced construction noise. Both CLT and Glulam are glued with solvent and formaldehyde-free PUR adhesive, the structure and cladding are mechanically fixed without the use of construction adhesives, and the timber cladding is left uncoated, resulting in a low VOC solid timber structure. The cypress cladding is left exposed to age naturally, requiring little ongoing maintenance despite the sea air. The CLT is durable in the aggressive marine environment of the beach house.
Suspended floors: Spruce CLT
Vertical supports or wall system: Posts - Spruce Glulam; Beams - Spruce Glulam
Curved composite beam: Spruce Glulam and Pine Plywood
Internal and external walls: Spruce CLT
Roof system: Beams - Spruce Glulam; Roof structure - Spruce CLT
Rainwater is harvested from all of the roofs. All fittings are low water use. Solar evacuated tubes in conjunction with a heat pump provide hot water, including for the hydronic floor heating inside the house.
A photovoltaic array with battery storage will be installed. Exterior cladding is uncoated. The use of insect screens and physical termite barriers avoids the need for harmful pesticides.
The elevated CLT construction minimises excavation and site disturbance, thereby protecting the native fauna and flora including the mature eucalypt tree canopy.
Cladding: Cypress Pine
Decking: Cypress Pine
External walkways and stairs: Cypress Pine
The passive solar design of the house floods the interior spaces with sunshine in winter, while blocking the heat of the sun in summer.
All-round insulation adds to the inherent insulation value of the solid CLT structure.
Concrete screeds on the CLT floors enhance the heat bankability of the solid CLT structure. The heat banks are passively heated in winter by the sun as well as solar hydronic floor heating.
In addition to employing cross-ventilation and breezeways to keep the interior environment fresh and airy, summer stack ventilation is used whereby cool air is drawn in through floor vents from the undercroft and hot air is exhausted through clerestory windows.
Daylighting is provided by all habitable rooms with windows on at least two sides. Internal finishes are low VOC while the use of construction adhesives has been reduced in favour of mechanical fixing.
Internal panelling: Pine
Door frames: Pine
Floor skirting: Pine
Joinery and cabinetry: Pine
Rails and balustrades: Tasmanian Oak
Stairs: Tasmanian Oak
Photographer: Josh Hill Photography and Marian Riabic/ Unique View Aerial Drone Photography
Builders: Ozbuild Design and Construction
Consultants: Aecom, REB Contracting Pty Ltd
Fabricators: KLH Massivholz, Austria
Designers: Ecobuild Design
Suppliers: Xlam Australia